MAINTAINERS: paravirt-ops maintainers update

Welcome to Alok Kataria, our new paravirt-ops maintainer.

Cc: Chris Wright <chrisw@sous-sol.org>
Cc: Alok Kataria <akataria@vmware.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>